The capital Kyiv remains under Ukrainian control as does Kharkiv in the east despite heavy Russian bombardment. Russian forces have seized Kherson in the south and have encircled urban centres in the region.

Here is a summary of the situation on the ground, based on statements from the sides, Western defence and intelligence sources and international organisations.

- The east

Kharkiv remains in Ukrainian hands despite intense bombardments, according to Western sources.

Russian forces are also pressing an offensive through the Russian-backed separatist Donetsk and Lugansk regions although how far they have penetrated remains unclear.

There has been heavy fighting around and inside the city of Sumy in northeast Ukraine, where Kyiv said there was intense Russian shelling and efforts underway to extract foreign students.

- Kyiv and the north

Kyiv remains under Ukrainian control, despite heavy bombardments, although Western observers have pointed to a major Russian column of hundreds of vehicle outside the city stationed around the Hostomel airfield.

There has been heavy fighting in the vicinity of Hostomel but the column has made little progress in recent days.

Ukrainian forces also retain control of the northern town of Chernihiv where there have been heavy civilian casualties in recent days.

- The south

Ukraine this week acknowledged that Russia had taken control of the southern city of Kherson, the first urban centre that Moscow has captured, but said locals were protesting against the occupiers.

Russia has besieged the strategic city of Mariupol where local authorities delayed a planned evacuation of residents, blaming Russian forces for breaking their temporary ceasefire.

Taking the city would give Russia chance to link forces pushing north from the annexed Ukrainian peninsula of Crimea with their forces from the east.

The famed port city Odessa remains in Ukrainian control and for now spared of fighting. But there are fears of a possible amphibious assault on the city with Russian warships lurking off the Black Sea coast.

Britain's defence ministry said Russian forces were were likely advancing on the southern port of Mykolayiv east of Odessa and that there was a "realistic possibility" forces would circumvent Mykolayiv to prioritise Odessa.

- The west

The west of Ukrainian remains largely spared from the fighting. The main western city of Lviv has become a hub for foreign diplomatic missions, journalists and Ukrainians seeking safety or seeking to leave the country.

- Casualties

Russia said Wednesday that 498 Russian troops had been killed in Ukraine, its first announced death toll.

Ukraine and Western sources claim that the real toll is far higher. Ukraine says around 10,000 Russian soldiers have been killed.

The UN said Wednesday it had recorded nearly 230 civilian deaths in Ukraine, including 15 children, warning the true toll was likely far higher.

- Refugees

Almost 1.37 million refugees have fled Ukraine in the week since the invasion, with over half going into Poland, according to the UN refugee agency.